1. Field of the Invention
The subject of the invention is a method and apparatus to generate and reproduce two-dimensional graphic objects for purposes of electronic or electromechanical reproduction.
2. Description of the Relevant Art
German Patentschrift Number DE-AS 24 22 464 teaches a method for the coding of characters for photoelectronic typesetting, and a decoding procedure associated with it. It also describes a character generator to produce the coded characters. The characters are coded as digital numbers based on a standard square corresponding to the coordinates of a starting point for the peripheral lines of the character. The characters are further defined in relation to variable parameters of these peripheral lines, such as the slope and the curvature. This is done by utilizing commands for a change in the curvature. The generation of a straight ascending or descending line, which is based on a command resulting from calculations affecting the slope, however, does require a large memory capacity for a large amount of slope data. This is especially the case when linear inclined line segments are to be generated in continuous fashion as peripheral lines of high quality typographical characters. Therefore, to form a peripheral line with a linear slope, a special command can be provided which involves incremental changes of Y-coordinate values. This special command defines how, starting from a starting point, the Y-coordinate is to be changed for each constant X-coordinate increment. Therefore, the listing of a number of X-increments, i.e., a number of calculation cycles for which a change in the Y-coordinate or the slope or the curvature must be calculated, is associated with each special command. The character generator so described requires a large memory capacity to store slope data from high quality typographical characters and also for the storage of the number of calculation steps which are required by the special commands. In addition, the calculations are relatively time consuming, especially the decoding procedure which requires lengthy calculations.
In addition, it is to be noted that all procedures which define the peripheral lines by means of slopes or curvatures are unstable and poorly based numerically, since they are characterized by unfavorable error progagation characteristics.
German Patentschrift Number DE-PS 29 53 600 describes a typesetter for the automatic generation of characters with the aid of a character storage device which stores the first and second coordinates for each character to be represented with reference to the starting points of two peripheral lines in a standard grid. Furthermore, a large number of linear sequential vectors which are based on the origin of the grid coordinate system and follow each other along the peripheral lines of the character also are stored as digital numbers. These vectors are respectively defined by digital numbers, which respectively define the first and second coordinate distances from the end of one vector to the next. This type of character generation results in poor quality characters, and the quality further deteriorates as the characters are enlarged. At the same time, improving the quality by reducing the length of the vectors significantly increases the amount of data to be processed.
It is the object of this invention to create a method and apparatus for the generation of graphic objects, where smooth aesthetic contours of high quality are generated with a minimum of calculation effort, data storage and memory requirements. It is also the object of this invention to create a method and apparatus where fast character transformation and subsequent decoding are guaranteed.
This objective, as well as further developments and improvements, is realized in accordance with the invention of the present application.
The generated graphic objects are of an excellent quality when using the method according to this invention. Also, only a small amount of data is required. It is of special advantage that a quick transformation of the generated characters is easily possible, and the subsequent decoding can be carried out at great speed.